Parents awaiting the arrival of their first child dream of sunlit days and peaceful nights, a domestic world in which, to paraphrase Garrison Keillor, all the fathers are helpful, all the mothers are patient, and all the children are way above average, and obedient, too.

But with each joyous birth also comes reality. Babies cry. Toddlers say No. Teenagers go silent. No wonder frazzled parents reach out to experts - the pediatricians, psychologists, and therapists who fill bookshelves and magazines with earnest advice on how to raise happy, healthy, successful children.

Modern parents did not invent anxiety, of course, as Ann Hulbert explains in "Raising America: Experts, Parents, and a Century of Advice About Children" (Knopf, $27.50). Even 100 years ago, the predecessors of Dr. Benjamin Spock were dispensing authoritarian do's and don'ts to mothers. (A father's role then was simply to be solicitous of his wife, not to change diapers.) Like their successors today, these advisers specialized in conflicting advice:

Don't play with your baby, warned one expert at the turn of the century.

Be affectionate, countered another.

Don't let your children sit in your lap, and don't kiss them - just shake hands with them in the morning, intoned a third.

Then there were those other enduring debates: Bottle or breast? Schedules or spontaneity? Discipline or leniency? Who could blame millions of confused parents for embracing the avuncular, reassuring Dr. Spock when his book appeared in 1946?

For Ms. Hulbert, a former senior editor at The New Republic, these conflicting child-rearing philosophies raised intriguing questions: Who were these men, anyway? (Yes, almost all were men, a gender imbalance that has improved only slightly today.) And what gave them the power to usurp the role grandmothers had traditionally played as reigning experts on bringing up baby?

As a child of the 1950s, Ms. Hulbert was raised as "a good Spock baby." But when it was her turn to have children - her daughter is now 11 and her son 14 - she did not rush to the parenting shelf at the bookstore.

"I was not an expert-addicted mother," she says. Even so, she wanted "to figure out where the experts' interests came from, what the sources of their advice were, and how it adds up."

As Hulbert studied a century of domestic and social history, she discovered that many early advice-givers were the sons of strong, adoring mothers and distant or difficult fathers. Despite the confidence they projected publicly and in print, they often proved to be less than successful in their private roles as husbands and fathers. Some worried that they might be a "mama's boy" and displayed what Hulbert calls a "deep ambivalence about women's power."

Still, that didn't stop them from "professionalizing" child-rearing. By defining motherhood as a vocation, these turn-of-the-century experts found a ready audience of middle-class women eager to upgrade the status of their maternal role.

"The era of the amateur mother was over," Hulbert says. Rather than relying on "uncertain instinct," mothers could now strive for "unhesitating insight."

"The notion of making child-rearing psychologically, socially, and spiritually a demanding and rewarding enterprise had a real appeal," Hulbert explains. "Plenty of women did not have other careers open to them."

But that professionalization carried a price for women. By raising the bar of parental skills ever higher, Hulbert says, the experts made everyone's expectations harder to fulfill.

Turning parenthood into a vocation also had the odd effect of making fathers more marginal, rather than less. Because breadwinning dads already had a full-time job, this new professionalism subtly excluded them.

Hulbert divides these paternalistic authorities into two camps. The "soft" ones advocated warm bonding with children, while the "hard" ones took a firmer position on discipline.

As family experts marched through the decades, the names changed, ranging from Luther Emmett Holt and G. Stanley Hall to Arnold Gesell, Bruno Bettelheim, T. Berry Brazelton, Penelope Leach, and John Rosemond. But the contrasting points of view remained firmly in place.

Early in the 1900s, a writer christened the era the Century of the Child. By 1925, a field called child development emerged. A new term, "the preschool child," joined the lexicon, and young children once known as "runabouts" now became "toddlers."

At the same time, earnest mothers and professionals were flocking to conferences with lofty titles, such as the National Congress of Mothers, held in Washington in the closing years of the 1890s, and the Conference on Modern Parenthood, convened in New York in 1925. Periodic White House conferences focused on the welfare of children, children in a democracy, early childhood development, and families.

By midcentury, high schools were also doing their part by teaching classes in family living.

Little by little, fathers came into their own, marking what Hulbert calls "a very notable change." In the second revision of his classic book, Spock placed more emphasis on fathers, a theme that has expanded everywhere since the 1960s. The fatherhood movement has also greatly influenced books in the past decade, Hulbert notes, with many authors placing a heavy emphasis on men's participation in family life.

Still, although more men are dipping into these books, women remain the primary buyers and readers. Over the decades a few women, led by Penelope Leach, have also joined the ranks of male advice-givers.

In an era of two-career families, the tone of advice has changed markedly, Hulbert finds. While Spock served as a "conversational confidant" to mothers who were home alone with their babies, today's authors present "almost managerial advice to extraordinarily busy people." Packaging is different, with experts offering more systematic tips. Even though they endorse maternal intuition, Hulbert says, authors still want to present information in a way that parents on the run can easily absorb.

Some things do not change. A century ago, Dr. Hall fretted that "home and family life have now shrunken." After World War I, Ernest Groves, a sociologist who wrote a book about "the drifting home," sounded thoroughly modern when he noted approvingly that "the family, like a good administrator, farms out more and more of its functions to school, church, and other organizations."

What began as the Century of the Child ended as the Century of the Expert. In the past quarter-century, the number of parenting books has increased fivefold.

How will social historians of the future judge the experts churning out books for today's anxious parents?

Given today's greater expertise and specialization, Hulbert thinks historians will have a harder time finding a clear-cut set of messages. But the same basic tensions exist between "hard" and "soft" experts.

As child-rearing manuals pour into bookstores and pile up on parents' nightstands, there may be something oddly reassuring about all this conflicting advice. It reminds parents that there is no single "right" way to raise their offspring.

"One reason we turn to experts in the first place is less to find answers than to find that our questions and confusions are shared by a lot of other people," Hulbert says. As parents discover that those questions have endured for a century, they feel more confident about their own instincts.

"In conversations among our friends, we're likely to find advice as useful to try out as we could ever find from experts," Hulbert says. "They're not as all-knowing as we thought they were."